166 



OOLITIC URASTERID^. 



Stellaster Berth andi, Wright, n. sp. PI. XXI, fig. 2. 



Body pentagonal, sides with arches much flattened ; tesserae thick and narrow, 

 thirty-six to forty pairs around the margin of one ray ; under surface of the disk covered 

 with small, close-set, equal-sized ossicles ; ambulacral channels wide ; dorsal discal ossicles 

 absent. 



Observation. — Since Mr. Sharp's specimen came into my hands for description a 

 plaster-mould has been kindly communicated to me by Professor Berthand, of Macon, 

 Saone-et-Loire, Prance. The original was collected from the ' Calcaire a Entroques,' 

 Macon. I mention it here, in connection with Stellaster Sharpii, Wr., as showing that 

 Goniaster was a type of the Asteriadse which prevailed during the first stage of the 

 Jurassic period, as the three forms we now know are all specifically distinct, and. belong to 

 the lower division of the Oolitic series. 



Genus— '{^'Khmm., Agassiz, 1835. 

 Uraster spiniger, Wright, n. sp. PI, XXt, fig. 1. Woodcut, fig. 41. 



Rays five, short, broad, curved, and petaloidal ; ambulacral areas wide ; margins 

 bordered by a series of small ossicles, which form beaded ridges on each side of the 

 ambulacral spaces. Ossicles support numerous small, short, blunt spines, which lie 

 in profusion on the sides of the rays, and similar spines appear to have clothed the 

 dorsal surface, and are seen "in situ" in the twisted portion of one of the rays, as 

 depicted in the annexed figure. 



The disk small in proportion to the width of the rays and diameter of the Starfish. 



Dimensions. — Diameter of the disk one half inch ; length of each ray one inch ; 

 breadth of a ray at its widest part four tenths of an inch. 



Description. — This Starfish was obtained from the Forest Marble, near Road, Wilts, 

 where it was collected by Dr. H. P. Parsons. The specimen came into my hands in a 

 very bad state, but by carefully backing it up with plaster of Paris I have been able to 

 develop a considerable portion of its anatomy. The small ossicles which occupied the 

 central portion of the ambulacral areas are absent, and there remains only the vacant 

 spaces they at one time filled. The margins forming the boundaries of the areas are 

 built up of a series of small ossicles, which are largest at the discal end, and diminish in 

 size towards the termination of the rays. They form a beaded structure of considerable 



